1. Field of the Invention
The present invention is concerned with a centrifugally driven filtration machine with continuous solids discharge, wherein the filtering surface is provided as a plurality of spaced filter elements within a centrifugal force field.
2. Discussion of the Relevant Art
The centrifugally driven filters are commonly used in the chemical, environmental and other industries for separating slurries into solid and liquid fractions. A typical centrifugal filter design is the so-called basket centrifuge, consisting of a perforated cylindrical bowl rotating about a vertical shaft. The inside surface of the bowl is lined with a replaceable filter cloth upon which the solids are retained, while the liquid is driven through the cloth by the centrifugal force. The operation is batchwise, i.e., the slurry feed must be periodically interrupted to allow for removal of the solids accumulated on the filter cloth by means of a scraping knife.
The performance of basket centrifuges has several drawbacks related to its batchwise operation, and to the limitations of the scraping knife action, which tends to compress a residual solids layer upon the filter cloth and thereby reduce its permeability.
A different approach to removing the solids from the filter cloth is to utilize the centrifugal force itself. For example, by reversing the filter cloth so the side originally facing the center of rotation during the filtration subsequently faces outwardly, i.e., in the direction away from the center.
For example, an apparatus has been proposed in U.S. Pat. No. 3,875,064 wherein a continuous filter cloth is mounted on a continuous moving belt traveling on a C-shaped assembly installed at the circumference of the centrifuge rotor.